This research is investigating the effects of maxillofacial surgery on the growth and adaptation of the craniofacial complex using Macaca mulatta as the experimental model. Mandibular growth after sagittal ramus osteotomies to advance the mandible, with and without detachment of the suprahyoid muscles, is being studied histologically, histochemically, cephalometrically and electromyographically. It has been hypothesized that distracting muscle forces will have adversed short-term effects after mandibular advancement. The results of these studies will have a direct and immediate impact on the related clinical problems of early maxillofacial surgical intervention and long-term stability (i.e., relapse) of surgical results.